Assertions in JUnit 4 and JUnit 5 suggestions

[Alex-Golub]

• Let's start reviewing the assertions available also in JUnit 4. Its under Junit 5 thus should be Junit 5
• blacklisted exception. Is marked deprecated according to Junit5 docs
• fast-forward marker. Example should be given

A valid fast-forward marker is a string that starts and ends with >> and contains at least four characters. Any character between the fast-forward literals is discarded.

>>>>
>> stacktrace >>
>> single line, non Integer.parse()-able comment >>

[lor6]

Thanks @Alex-Golub I've merged the PR and clarified point #1 in the article.
I'll add an internal improvement to look closer into points 2 and 3.